A gas-insulated switchgear having a bus container is provided between a three-phase high voltage power supply and an air power transmission line in a transformer substation or the like, to detect an abnormal current such as lightning surge and break the current. It has a bushing to receive electricity transmitted from the three-phase high voltage power supply, a bus container containing a three-phase bus conductor which is gas-insulated to supply electricity from the bushing to the gas circuit breaker, a disconnector, an earthing device and the like. In recent years, to reduce the installation area for the gas-insulated switchgear and to reduce transportation cost, downsizing of the respective devices such as the gas circuit breaker is required.
An invention of a double-bus gas-insulated switchgear with the purpose of downsizing in a height direction is described in patent document 1. This invention is configured as follows. A line-side device is connected to an upper terminal of a vertically-arranged circuit breaker, and a branch bus branching in a downward direction and a horizontal direction is connected to a lower terminal of the circuit breaker. A first bus-side disconnector is laterally arranged on the downward directional branch of the branch bus, and a second bus-side disconnector is laterally arranged on the horizontal directional branch of the branch bus. A first main bus is connected in the horizontal direction of the first bus-side disconnector, and the first main bus is connected in the downward direction of the second bus-side disconnector.
Further, an invention of a gas-insulated switchgear with the purpose of suppressing the height directional size and the installation area and reducing transportation cost is described in patent document 2. This invention is configured such that at least a bus disconnector and a main bus are provided at one side of a circuit breaker as a central device, and at least a line earthing switch, an arrester, a current transformer, and a cable head are provided at the other side.